In the silicone wafer manufacturing industry, a wafer may arrive at a point on the production line in a wide variety of states of processing. Processing of silicone wafers normally changes their surface properties and/or surface texture. It is desirable to be able to automatically determine the level of processing of such a wafer during a production process so that, dependent on the level of processing, appropriate steps can be taken.
Currently, electronic sensing arrangements are used in the silicone wafer fabrication industry to detect the presence or absence of a wafer. The sensors sense the intensity of the light reflected off of a wafer to be able to detect a wafer's presence. The absence or presence of the wafer changes the amount of light received by the sensor. The quantity of light received by the sensor from a wafer can be related to the absence or presence of that wafer.
However, it is difficult to stabilize the amount of ambient light that is reflected off the wafer that may also be detected by the sensor. Further, a slight difference in the material making up the wafer may result in a slightly darker or lighter wafer, thereby resulting in false readings.